ZINDOS

The ZINDO/1 method is the most suitable semi-empirical method in HyperChem for determining structures and energies of molecules with first or second transition row metals. 

The ability to perform molecular orbital (MO) calculations on metals is extremely useful because molecular mechanics methods are generally unable to treat metals. This is because metals have a wide range of valences, oxidation states, spin multiplicities, and have unusual bonding situations (e.g., dtt-pjt back bonding). In addition, the nondirectional nature of metallic bonding is less amenable to a ball and spring interpretation. 

Conversely, these factors dictate that molecular orbital calculations on metals yield less reliable results than with organic compounds. 

ZINDO/S is parameterized to reproduce spectroscopic transitions, therefore we do not recommend using this method for geometry optimization. You can obtain better results by performing a singlepoint calculation with ZINDO/S on a geometry obtained from the Model Builder, an optimization using one of HyperChem s other methods, or an external source. 

For transition metal complexes with several possible spin arrangements, a separate calculation within each spin multiplicity may be required to find the ground state of the complex. 

---

After yon choose the com pn tat ion method and options, you can use Start bog on the file menu to record results, such as total energies, orbital en ergies, dipole m om en Ls, atom ic charges, en Lhalpics of formalion (foritieCNDO, IN DO, MIXDO/3, MNDO, AMI, PM3, ZINDO/1, and ZINDO/S mclh ods), etc. 

ZINDO/1 IS based on a modified version of the in termediate neglect of differen tial overlap (IXDO), which was developed by Michael Zerner of the Quantum Theory Project at the University of Florida. Zerner s original INDO/1 used the Slater orbital exponents with a distance dependence for the first row transition metals only. Ilow ever. in HyperChein constant orbital expon en ts are used for all the available elein en ts, as recommended by Anderson. Friwards, and Zerner. Inorg. Chem. 2H, 2728-2732.iyH6. 

ZINDO/S is an INDO method paramcteri/ed to reproduce LV visible spectroscopic transitions when used with the singly excited Cl method. It w as developed in the research group of Michael Zerner of the Quantum fheory Project at the University of Florida. 

As with the other sem i-cm pineal methods. HyperGhem s im p le-meiitation of ZINDO/1 is restricted to spin multiplicities up to a quartet state. ZIXDO/1 lets you calculate the energy slates in molecules containing transition metals. 

The basic equations of ZINDO/1 are the same as those m IXDO, except I orL i y. In stead of usiri g th e electron egativity in INDO, ZlNDO/l uses th e ion i,ration potential for computing Llj,... 

The mixed model used m ZINDO/1 is identical to that used in CXDO an d INDO if there is no d-orbital in volved in the t iian turn... 

The algorithms in Z[ DO/S are almost the same as those in ZlNDO/1, except of the one-center two-electron integral, b . ZINDO/S uses em pirical value of in stead of ii sin g ah initio vaine in terms of the Slater orbitals. 

ZlNDO/S is differen t from ZINDO/1 because th ey use differen t algorithms in computing the Coulomb integrals. Hence the two et uation s used in th e rn ixed m odel in ZINDO/1 are also employed... 

The Zerner s INDO method (ZINDO) is also called spectroscopic INDO (INDO/S). This is a reparameterization of the INDO method specihcally for the purpose of reproducing electronic spectra results. This method has been found to be useful for predicting electronic spectra. ZINDO is also used for modeling transition metal systems since it is one of the few methods parameterized for metals. It predicts UV transitions well, with the exception of metals with unpaired electrons. However, its use is generally limited to the type of results for which it was parameterized. ZINDO often gives poor results when used for geometry optimization. 

The one exception to this is the INDO/S method, which is also called ZINDO. This method was designed to describe electronic transitions, particularly those involving transition metal atoms. ZINDO is used to describe electronic excited-state energies and often transition probabilities as well. 

Intensities for electronic transitions are computed as transition dipole moments between states. This is most accurate if the states are orthogonal. Some of the best results are obtained from the CIS, MCSCF, and ZINDO methods. The CASPT2 method can be very accurate, but it often requires some manual manipulation in order to obtain the correct configurations in the reference space. 

ZINDO is an adaptation of INDO speciflcally for predicting electronic excitations. The proper acronym for ZINDO is INDO/S (spectroscopic INDO), but the ZINDO moniker is more commonly used. ZINDO has been fairly successful in modeling electronic excited states. Some of the codes incorporated in ZINDO include transition-dipole moment computation so that peak intensities as well as wave lengths can be computed. ZINDO generally does poorly for geometry optimization. 

The semiempirical techniques available include EH, CNDO, INDO, MINDO/3, ZINDO, MNDO, AMI, and PM3. The ZINDO/S, MNDO/d, and PM3(TM) variations are also available. The semiempirical module seems to be rather robust in that it did well on some technically difficult test calculations. 

Configuration Interaction (or electron correlation) improves energy calculationsusing CNDO, INDO, MINDO/3, MNDO, AMI, PM3, ZINDO/1, and ZINDO/Sfor these electron configurations... 

In order to conserve the total energy in molecular dynamics calculations using semi-empirical methods, the gradient needs to be very accurate. Although the gradient is calculated analytically, it is a function of wavefunction, so its accuracy depends on that of the wavefunction. Tests for CH4 show that the convergence limit needs to be at most le-6 for CNDO and INDO and le-7 for MINDO/3, MNDO, AMI, and PM3 for accurate energy conservation. ZINDO/S is not suitable for molecular dynamics calculations. 

CNDO, INDO, MINDO/3, ZINDO/1, and ZINDO/S Methods... 

ZINDO/1 and ZINDO/S are Dr. Michael Zerner s INDO versions and used for molecular systems with transition metals. ZINDO/1 is expected to give geometries of molecules, and ZINDO/S is parametrized to give UV spectra. 

---